The annual cycle of the Copepods, Cladocera, Appendicularians, Chaetognatha and Cnidaria has been observed in a coastal area in front of Boulogne-sur-Mer. Four species of Copepods amount to some 70% of the whole zooplankton. These herbivorous animals become especially abundant during the phytoplankton blooms with yield which seems to be more important during the autumn than during the spring. Yearly the Appendicularians offer four maxima agreeing with the transport of patches by the currents. The Chaetognatha are only present during the autumn. The cycle of Cladocera is described with respect to their fecundity. The Ctenaria show blooms succeeding those of herbivorous animals. The study of relations between the zooplankton trophic levels suggests that, in this coastal area, the biomass of omnivorous detritivorous animals is at least as important as that of herbivorous ones. Therefore, an important part of energy enters the pelagic food chain through the omnivorous detritivorous animals, feeding on detritus and suspended organic matters. The chronological succession of the different consumers levels is shown. The communities considered here exhibit the characters of a neritic coastal zooplankton and look quite similar to the populations observed along the Belgian coast.